CODEWITHSUNDEEP
javaubuntuhadoopmapreduceword-count
d84_n1nj4
d84_n1nj4

Reputation: 1852

"Cannot find symbol" error in Hadoop WordCount Example

I am trying to work through this Hadoop MapReduce Word Count example given in the book Data Analytics with Hadoop which had me setup a Hadoop pseudo-distributed development environment. So now I am trying to run a Word Count example. I downloaded the .java files, WordCount folder, from Hadoop Fundamentals. The code given in the book to start this process is:

hostname $ hadoop com.sun.tools.javac.Main WordCount.java

I run this and receive the following errors:

hadoop@gh0st-VirtualBox:/home/gh0st$ hadoop com.sun.tools.javac.Main Downloads/WordCount/WordCount.java
Downloads/WordCount/WordCount.java:32: error: cannot find symbol
        job.setMapperClass(WordMapper.class);
                           ^
  symbol:   class WordMapper
  location: class WordCount
Downloads/WordCount/WordCount.java:33: error: cannot find symbol
        job.setReducerClass(SumReducer.class);
                            ^
  symbol:   class SumReducer
  location: class WordCount
Note: Downloads/WordCount/WordCount.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
2 errors

The WordMapper.java and SumReducer.java files are located in the same WordCount folder from which I'm running the WordCount.java file. I'm not sure where to start from here considering all I read regarding this. My $JAVA_HOME is /usr/lib/jvm/java-7-openjdk-amd64/. My $CLASS_PATH is $HADOOP_HOME/share/hadoop/common/hadoop-common-2.7.3.jar. I'm not sure what other information is needed to fix this issue--I'll add whatever else is needed. The following links are what I looked at and tried:

Hadoop Problems

Compilation Problems

I am using Ubuntu 14.04 within VirtualBox.

Upvotes: 1

Views: 3259

Answers (2)

Aymen Alsaadi
Aymen Alsaadi

Reputation: 1517

This worked for me:

  1. Export Hadoop classpath:
export CLASSPATH=`hadoop classpath`
  1. Check the path does exist:
echo $CLASSPATH
  1. Run all of them at the same time:
javac -d . WC_Runner.java WC_Mapper.java WC_Reducer.java

Upvotes: 1

d84_n1nj4
d84_n1nj4

Reputation: 1852

So after some deep digging, I found the answer. The answer is in the comment in the following link: Driver Class Compilation Error

I had to compile all the files together. The new code looks like this:

hadoop com.sun.tools.javac.Main Downloads/WordCount/WordCount.java Downloads/WordCount/WordMapper.java Downloads/WordCount/SumReducer.java

Hope this helps someone!

Upvotes: 4

Related Questions